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#92927 04/18/05 12:17 PM
Joined: May 2004
Posts: 697
D
Dave55 Offline OP
Member
I hope you'll excuse my ignorance, but I find parallel conductor sizing for a service confusing. I'm going to be installing a 3PH, 4-wire, 1,000-amp overhead service. I'd appreciate references to the 2002 NEC so I can understand it. I'd also appreciate wire smaller than 500kcmil. I don't recall the pipe size, but it took 2 of us over an hour to install the service heads (500kcmil just doesn't bend well).

Thanks,
Dave

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Joined: Aug 2003
Posts: 1,374
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Moderator
I'm not sure why you would have 500 kcmil, since it is a 380 amp conductor, and according to 240.4(C) it would be either grossly uindersized or grossly oversized.

The code reference to read would be 310.4 and 250.122(F), for starters.


Ryan Jackson,
Salt Lake City
Joined: May 2004
Posts: 697
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Dave55 Offline OP
Member
Thanks, Ryan.

I'm coming up with (3) 400kcmil, or (4) 250kcmil with a 2/0 EGC. I assume the 75 degree C table is used because of terminations. I don't understand the importance of 240.4(C) in light of 310.4 (...to form a single conductor).

Dave

Joined: Jan 2004
Posts: 1,507
G
Member
What type of service is it Delta? Wye? How are you including a GEC? Do you mean the Grounded conductor? Another issue is, Are all your conductors in the same raceway? Could you use a bus bar riser?


George Little
Joined: May 2004
Posts: 697
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Dave55 Offline OP
Member
The EGC (copper) per Table 250.122, but not in the raceway. It's a Delta 3PH. All the conductors would be in the same raceway (4 per RMC, anyway)...and what is a bus bar riser???

Dave

Joined: Jan 2004
Posts: 1,507
G
Member
The Grounded Conductor / Neutral run with the Service conductors is sized per 220.22 & 250.24(B)
As to what is a buss bar riser? It is a Service that uses bus bars instead of wires.


George Little
Joined: Feb 2001
Posts: 308
S
Member
How about 5-3/0's? Then you could use 2" instead of 2-1/2". The utility might not like that though.


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